complete -xc nvm -n __fish_use_subcommand -a ls -d "List available versions matching <regex>"
complete -xc nvm -n __fish_use_subcommand -a use -d "Download <version> and modify PATH to use it"
complete -xc nvm -n __fish_use_subcommand -a --help -d "Show usage help"
complete -xc nvm -n __fish_use_subcommand -a --version -d "Show the current version of nvm"

nvm complete